Total hip arthroplasty [FIG. 6] has been used since the 1960s for the treatment of destructed hip joints. Many surgical approaches have been used such as the anterior Smith-Peterson Approach, Watson-Jones Approach, Hardinge Approach, Direct lateral approach, Posterolateral approach (Modified Gibson approach), and Posterior Approach (Muller Approach). Each approach has advantages and disadvantages. For example, in the anterolateral approach, the Gluteus medius and Gluteus minimus are vulnerable to injury during the procedure or sometimes the muscle fibers are cut for easy insertion of the acetabular socket and then are repaired after the procedure. However, no matter how well or tightly they are repaired, muscle power is decreased, the time for rehabilitation is delayed, and sometimes patients complain of limping because of the weakness of the muscles. In the posterior or posterolateral approach, the short external rotator muscles (Piriformis, Gemellus superior and inferior, Obturator internus and externus, Quatratus femoris) are cut during the operative procedure. They may be repaired after the procedure but still remain very weak. Therefore, the postoperative rehabilitation is delayed and sometimes the artificial joint is dislocated because of the weakness of the muscles.
Many efforts have been made to give the patients less trauma during the operation and to permit early rehabilitation by performing a small incision.
There are several kinds of minimally invasive surgeries for total hip arthroplasty such as a one-incision anterior approach, one incision anterolateral approach, one-incision posterolateral approach, and two-incision approach. The two-incision approach (anterior and posterior incision) was made to be minimally invasive, minimizing injury not only to the skin but also to the muscles, ligaments, and joint capsules.
The present invention is a two-incision procedure. The anterior incision (3) is for acetabular socket insertion, and the posterior incision (4) is for the femoral stem insertion.
The previous method of the two-incision procedure was performed with the patient in a supine position [FIG. 1], causing femoral stem reaming to be much more difficult. Injury to the sciatic nerve was more likely to develop because the femoral insertion site was near the sciatic nerve, and finding the muscle plane between the Gluteus medius and Piriformis muscle in the supine position was more difficult. Also, in the previous technique, the anterior incision (1) approaches between the Sartorius muscle (7) and Tensor fascia lata muscle (8) and between the Rectus femoris muscle (18) and Tensor fascia lata muscle (8) distally which is more likely to injure the lateral femoral cutaneous nerve (11) because the incision is near the distribution of the lateral cutaneous nerve (11).
The present invention of the two-incision minimally invasive technique is different from the previous method in that the operation is performed with the patient in the lateral decubitus position [FIG. 2] which provides a much easier and safer position for the femoral stem insertion, and the anterior incision (3) approaches through a safer area between the Gluteus muscle (Gluteus medius and minimus) (9) and Tensor fascia lata muscle (8), rather than between the Sartorius muscle (7) and Tensor fascia lata muscle (8).